Experiment: Part A - Screening test for nitrite Before determining the concentration of nitrite, you need to first ascertain which samples have nitrite present in them. The initial stage in the investigation is therefore to carry out a qualitative test on the samples. 1. Prior to determination of nitrite in the samples, aliquot equal volumes of Griess 1 to Griess 2 and leave for ten minutes to equilibrate. 2. To seven separate plastic tubes add samples as below: (1) 100 d of sample 1 100 l of sample 2 100 wl of sample 3 100 ml of sample 4 (v) 100 ull of sample 5 (vi) 100 ul of sample 6 (placebo) (vil) 100 l of sample 7 (prednisone) 3. To each add: 100 ml of mixed Griess 1 and Griess 2 solution. 4. Create your own scale for determination of colour intensity and note the intensity/colour change observed. Indicate whether nitrite is present or absent from the sample. Experiment: Part A - Screening test for nitrite Before determining the concentration of nitrite, you need to first ascertain which samples have nitrite present in them. The initial stage in the investigation is therefore to carry out a qualitative test on the samples. 1. Prior to determination of nitrite in the samples, aliquot equal volumes of Griess 1 to Griess 2 and leave for ten minutes to equilibrate. 2. To seven separate plastic tubes add samples as below: (1) 100 d of sample 1 100 l of sample 2 100 wl of sample 3 100 ml of sample 4 (v) 100 ull of sample 5 (vi) 100 ul of sample 6 (placebo) (vil) 100 l of sample 7 (prednisone) 3. To each add: 100 ml of mixed Griess 1 and Griess 2 solution. 4. Create your own scale for determination of colour intensity and note the intensity/colour change observed. Indicate whether nitrite is present or absent from the sample